An area of low pressure will pass north of our area tonight while a cold front attached to this low moves SE across the area. There will be some snow showers and flurries in the Northland tonight with the best chance for seeing some accumulation (1″ or less) confined to northern Minnesota into the Arrowhead, generally north of Duluth.
A quiet weather day in our area for Monday, but this will be followed by a round of accumulating snow on Tuesday as low pressure moves ENE out of the Dakotas. This system will bring a 6-hour period of enhanced lift which combined with cold temperatures should lead to a fluffy snowfall with higher than usual snowfall ratios, perhaps reaching 20:1 instead of the normal 10:1. The fast movement of this system should keep snow amounts <6″ on Tuesday, but a swath of about 3-4″ (isolated 5″ totals) is looking quite likely in much of the Northland.
Here’s a look at the HRRR model simulated radar forecast ending Midnight tonight — Snow showers are most likely tonight north of that black line on map.
SNOW ON TUESDAY
A fast-moving area of low pressure is forecast to move ENE out of the Northern Plains on Tuesday. This system looks to bring accumulating snow to much of northeast Minnesota and northwest Wisconsin on Tuesday.
Snow is expected to spread west to east across the Northland Tuesday morning, beginning ~2 AM to 4 AM in western areas, and generally after 5 AM in the Arrowhead and in northwest Wisconsin (timing may change a bit over the next 24 hours)
For Duluth: Snow arrives Tuesday morning 4 AM to 6 AM, snow ends Tuesday afternoon ~2 PM.
European computer model simulated radar forecast valid Midnight to 6 PM Tuesday (snow in blue colors).
Here’s my snowfall forecast valid for Tuesday, December 21, 2021.
Snowfall amounts and gradients may shift a bit in later updates since this event is still over a day away.
ACTIVE WEATHER PATTERN
An active weather pattern/storm track may develop from the Western U.S. to the upper Midwest and Great Lakes late this week into next week as multiple low-pressure systems eject eastward or northeastward out of the Rockies.
Exact storm tracks will continue to change on a daily basis until these event gets closer, and those storm tracks will be critical in determining where the rain-snow line sets up, and where and how much precipitation will see, but the main takeaway from model guidance is for a pretty active weather pattern setting up from late this week into next week.
Note: Computer models have been hinting at one system impacting the region ~December 24-25, with another system ~December 26-28, with another one or more toward the end of the year.
Here’s the 500mb forecast valid December 23 to December 29, 2021 — Troughs/unsettled weather in blue, while generally quieter weather/ridging in orange, red and purple colors.
Both EPS and GEFS ensemble models show around an inch or more of precipitation for much of the Northland thru December 31st — Just using a normal 10:1 snow to liquid ratio would give us 10″ of snow, if all the precipitation were to fall as snow, but remember snowfall ratios vary with each event (temperature and wind speed dependent, among other factors) and this will also affect snowfall amounts.
Plenty of arctic air lurking well to our north with temperatures in the single digits, teens and 20s below zero across northern Canada this afternoon. Even colder in parts of Russia where temperatures range from around -30 to -50 F today.